The present invention relates in general to a laser transmitter, and, more particularly, to a system and method for checking and calibrating, if necessary, the orientation of a laser beam defining a plane through which the laser beam is rotated.
Laser light systems have been employed in numerous surveying and construction applications. In one type of system, a laser light transmitting device provides a rotating laser beam which establishes a reference plane. Typically, the rotating laser beam is used to provide a continuous plane of light that creates either a constant horizontal bench mark of elevation or a selected plane over an entire work area. The laser light is either detected by the naked eye or by one or more laser beam detectors, placed at considerable distances from the transmitting device. Various construction tasks may be performed based on the visual perception of the laser light. Alternatively, detectors may be used to intercept the rotating laser beam and determine a proper elevation and grade at selected points throughout the work area.
In one type of laser light transmitting device, the plane of light is produced by projecting the beam generally upward and then deflecting the beam ninety degrees with a pentaprism or penta-mirror assembly. The pentaprism assembly is rotated about a vertical axis, thus rotating the beam and defining the reference plane. The laser light transmitting device is typically calibrated at the time that it is assembled so that the laser beam defines a substantially horizontal plane of light when the transmitting device is properly setup. However, the transmitting device may become miscalibrated due to environmental conditions or rough handling. The laser light transmitting device therefore must be repeatedly checked to ensure that it is still properly calibrated.
One prior art method for checking the calibration of a laser transmitting device involves positioning the laser transmitting device so that it is substantially level. The transmitting device may be leveled manually using leveling vials or automatically using any of a variety of techniques known in the art. Once level, the laser transmitting device is activated so that the laser beam defines a plane which will be substantially horizontal if the transmitting device is properly calibrated.
The laser transmitting device is then aligned with a target which is positioned an approximate set distance from the transmitting device, for example 200 feet. The transmitting device may be aligned by aiming a known point on the device in the direction of the target. The known point is typically aligned with a set axis in the transmitting device, i.e., along the X or Y leveling axes. The position of the laser beam on the target is noted. The transmitting device is rotated through the remaining three coordinate axes with the position of the laser beam on the target being noted for each axis. The position of the laser light on the target for each of the four coordinate axes will be substantially the same if the transmitting device is properly calibrated. Any deviation signifies that the transmitting device is misaligned and calibration is needed.
This method is time consuming and labor intensive as it requires an operator to walk back and forth between the transmitting device and the target for each measurement. Further, the operator must make the measurements manually, calculate the deviation and determine the required adjustments. As a result, field calibrations are probably not performed as often as necessary.
Accordingly, there is a need for improved system for checking and calibrating a laser transmitting device. Preferably, such a system would be automatic and easy to operate requiring little or no intervention on the part of the operator.